两种励磁方式漏磁内检测的简化试验对比

Simplified test comparison of two excitation modes in MFL internal inspections

为系统对比轴向和周向励磁方式的漏磁内检测技术对于不同角度缺陷检测结果的准确度,设计了简化的工程对比试验。该试验选取平面钢板作为试验样板,在钢板上制作不同角度的缺陷,同时开发平板结构漏磁检测样机,通过改变励磁方向来模拟轴向励磁漏磁和周向励磁漏磁内检测。利用平板结构漏磁检测样机,以上述两种励磁方式对平面钢板上的缺陷进行漏磁检测并得出检测信号。对比轴向励磁漏磁内检测和周向励磁漏磁内检测对同一缺陷所得的不同检测信号,结果表明:对于与轴向平行或者夹角不超过30°的缺陷,周向励磁漏磁内检测技术的检测结果准确度高;对于与轴向夹角大于30°的缺陷,轴向励磁漏磁内检测技术的检测结果准确度高。

In order to compare systematically the inspection accuracy of axial-excitation magnetic flux leakage(MFL) internal inspection and circumferential-excitation MFL internal inspection on defects of different angles, a simplified engineering comparison test was designed. In the test, a flat steel plate on which defects of different angles were made was used as the test sample, and a magnetic leakage detection prototype with flat structure was developed to simulate axial and circumferential excitation MFL internal inspection by changing the direction of the excitation. By virtue of the MFL detection prototype with flat plate structure, MFL inspection was performed to the defects on the flat plate based on axial excitation and circumferential excitation, and the MFL signals were acquired. The following test conclusions are reached by comparing the detection signals of the same defect acquired from axial-excitation MFL internal inspection and from circumferential-excitation MFL internal inspection. The circumferential-excitation MFL internal inspection results are more accurate if the defect is parallel to the axial direction or the included angle between the defect and the axial direction is equal or less than 30°, and the axial-excitation MFL internal inspection results are more accurate if the included angle between the defect and the axial direction is more than 30°.